The invention is directed to a miniature centrifugal separator comprising a circular flow tube having a swirl-inducing vane structure in its upstream end, and two or more clean air take-off tubes stacked one behind another along the flow tube axis. Swirl action of the vanes produces an outward migration of the dust particles toward the flow tube wall. A conventional induced draftfan draws a stream of concentrated dust from the tube wall area beyond the entry zone of the first take-off tube; partially cleaned gas is caused to flow into the first clean air take-off tube. The partially cleaned gas flows into a flaring (frusto-conical) section of the first take-off tube where it encounters the second take-off tube. Centrifugal forces present in the still-swirling gas cause dust particulates to be thrown into the flaring space surrounding the second tube; purified gas flows through the second take-off tube to the point of use. Dust particulates are removed by the aforementioned fan.
Each take-off tube provides a distinct dust separation zone. By suitably controlling the flow resistances of the different zones it is believed possible to adjust the component flows and component energy consumptions, to thereby obtain relatively high total collection efficiency. The length of each tube and its position relative to the main flow tube are preselected in accordance with the swirl angle so that the dust particles are enabled to complete approximately one swirl revolution before reaching the next separation zone. As before noted, the invention seeks to achieve high collection efficiency in a relatively small length flow tube.